1. Field of the Invention
The present invention relates to a treatment device for an endoscope for use in inserting the device into a body to capture and remove a polyp with a treatment portion disposed in a tip end of the device, or retaining the device in the body while capturing the polyp in the device.
2. Description of the Related Art
A treatment device for an endoscope, which captures and medically treats a polyp in a body, includes: a mode comprising: a treatment portion which projects from a tip end of a main tube to form a loop for treatment and which can freely be retracted into the main tube in a tip end of an operation wire inserted into the main tube of a flexible elongated tube to be inserted into the body. Living tissues such as a polyp are captured and fastened by the loop of the treatment portion, and thereafter the loop is retracted into the main tube so that the captured polyp is removed/treated.
However, since the polyp to be captured is a soft elastic member encapsulated in a body fluid small in contact angle and having a high-viscosity wet state, it is difficult to retain/capture the polyp by the loop for treatment. As known examples which solve this disadvantage, there are a structure in which an engagement needle is embedded in a rope material of the treatment portion, and a needle tip projects inside a loop to pierce and engage with the polyp (Jpn. Pat. Appln. KOKAI Publication No. 2000-271146), and a structure in which one wire of the rope material of the treatment portion is cut, and a cut end projects inside the loop to function as a capture needle of the polyp (Jpn. Pat. Appln. KOKAI Publication No. 2000-107198).
On the other hand, in Jpn. UM Appln. KOKOKU Publication No. 6-3549, a structure is disclosed in which a large number of slip stopper chips are attached later and fixed to a wire material of the loop for treatment, a tip end of each slip stopper chip projects inside the loop for treatment to form an engagement projection, and capturing properties of the polyp are enhanced.
Any capturing properties enhancement structure of the above-described known examples is a structure which allows a needle-shaped/projecting material rich in rigidity to project inside the loop. Therefore, when the loop is retracted and stored in the main tube, the needle-shaped/projecting material is superimposed and united to interfere with a treatment portion member or contact an inner periphery of the main tube, and a resistance in the retraction into the main tube increases to make an operation difficult. Moreover, a formation operation comprising: accurately determining a projection direction and fixing a large number of the above-described engagement needles/slip stopper chips onto the rope material of the treatment portion is laborious, requires a number of manual operations, and is inferior in processability.
Furthermore, for the above-described wire cut mode, a formation operation comprising: cutting one wire of a wire rope having a remarkably small diameter and allowing the wire to project in an accurate direction is remarkably laborious and bad in processability. Additionally, the wire rope is broken because of a strength drop, and a projecting posture of the engagement needle formed by bending the cut end of the wire accommodated in the tube is deformed so that engagement properties are degraded. As another disadvantage, the loop for treatment is caught by the rope material to which the loop is bonded, and cannot sufficiently be enlarged/deformed because of a self elastic force.